Re: [6.18.y] bonding: please apply 11ea9b8a88dd and 70fc6649b36c

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Oct 30, 2026 at 10:51:18PM +0000, Struan Bartlett wrote:
> Hello,
> 
> Please apply these two mainline commits (v7.0) to 6.18.y, in this
> order:
> 
>   11ea9b8a88dd ("net: bonding: use workqueue to make sure peer notify updated in lacp mode")
>   70fc6649b36c ("net: bonding: move bond_should_notify_peers, e.g. into rtnl lock block")
> 
> 70fc6649b36c fixes a fault from 7a9214f3d88c ("bonding: ARP monitor
> spams NETDEV_NOTIFY_PEERS notifiers") that is present in 6.18.y: in
> active-backup mode with the ARP monitor, if bond_ab_arp_commit() fails
> over while a peer notification is pending, bond_activebackup_arp_mon()
> decrements send_peer_notif a second time, on the strength of
> should_notify_peers computed before the failover. The counter wraps
> from 0 to UINT_MAX, and the bond then sends NETDEV_NOTIFY_PEERS every
> arp_interval for years. At boot this happens whenever a backup slave's
> link comes up shortly before the primary's. On our servers FRR's zebra
> counted each notification as the bond's link coming up, and ntpd never
> rescanned its interfaces, so the clock went unsynchronised.
> 
> 11ea9b8a88dd is a prerequisite: it adds bond_peer_notify_may_events(),
> which 70fc6649b36c uses. Neither commit is tagged for stable. Both
> apply cleanly, in this order, to v6.18.60 and v6.18.9.
> 
> Testing: Debian's 6.18.9-1~bpo13+1 kernel, booted in a VM, with the
> bonding module built from v6.18.9 against Debian's headers. A
> reproducer (two network namespaces: an active-backup bond with the ARP
> monitor over two veths to a bridge holding the ARP target; it fails
> over to the backup with num_grat_arp 255, then lets the ARP monitor
> fail back to the primary with num_grat_arp 1 while a notification is
> pending) counted the bond's NETDEV_NOTIFY_PEERS events for 3 s just
> after the failback and, if there were any, for 3 s again 30 s later,
> after the 255 would have run out. With arp_interval 100, a bond that
> notifies on every ARP monitor run sends about 30 in 3 s:
> 
>   bonding module                         after  30 s later
>   Debian's                                 29     28
>   v6.18.9, unchanged                       29     29
>   v6.18.9 + 11ea9b8a88dd + 70fc6649b36c     0      -
> 
> Neither commit applies to 6.12.y, so I am sending a minimal equivalent
> patch for 6.12.y separately, with the reproducer:
> "[PATCH 6.12.y] bonding: re-check pending peer notification under RTNL
> in ARP monitor".
> 
> An AI coding assistant (Claude, model claude-opus-5-5) helped trace
> the fault, wrote this request and the reproducer, and built and ran
> the tests above under my direction. I have reviewed this request.
> 
> Thank you,
> 
> Struan Bartlett
> 

Now queued up, thanks.

greg k-h